Teas and extracts from Harpagophytum procumbens have long been recommended in the folk medicine for various indications, for example, indigestions of different kinds, rheumatic diseases, obstetrics, wound healing, arterial calcification, allergic diseases, etc.
There have been extensive reports on the plant, its components and their chemical structures; in contrast, pharmacological/toxicological works are found much less often. A literature survey can be found in Erfahrungsheilkunde 2, 1995, pages 74 to 79. Studies with various extracts of the secondary root with water, methanol and n-butanol can be found in A. Erdxc3x6s et al. in xe2x80x9cPlanta medicaxe2x80x9d, Journal of Medicinal Plant Research, 1978, vol. 34, pages 97 to 108. This work supports earlier findings according to which such extracts exhibit a medium-potent, significantly analgetic activity which is lower, however, than that of acetylsalicylic acid. Further, this work is also led to the conclusion that the glycoside harpagoside is probably not the only substance to account for the analgetic and antiphlogistic effects achieved. Evidence of this is furnished by the activity of the highly purified extract H 25 C3 which contains 85% of harpagoside, but fails to exhibit a significantly better effect than the other extracts in all of the experimental models.
From reviews dealing with the suitability of extracts from Radix Harpagophyti in treatments of rheumatic diseases (Wenzel, P., Wegener, T., DAZ 135, 1131-1144), it can be seen that Harpagophytum extracts have medium-potent analgetic and strong anti-phlogistic activities. For both indication areas, as a rule, a mechanism of action is claimed which is experimentally determined by the inhibition of cyclooxygenase activity (Simmet et al., Thrombosis Res. 67, 123-134, 1992).
It has been the first object of the invention to provide a purified and as well as possible standardized extract from Harpagophytum procumbens which possibly has a higher efficiency than highly purified harpagoside. It has been a further object of the invention to employ other suitable starting materials as well.
These objects have now been surprisingly achieved by extracts obtainable by dissolving aqueous and/or aqueous/alcoholic (C1-C3) Extract spissum and/or dry extracts in water saturated with n-butanol, extracting with n-butanol saturated with water, and removing the n-butanol in vacuo. The n-butanol is removed as completely as possible. It has further been established that, in addition to Harpagophytum procumbens, Harpagophytum zeyheri DENCE can be used with virtually equal success. Thus, it is by all means possible to employ these two starting drugs alone or in admixture.